In air ducts for commercial and residential installations, for heating, ventilating and air conditioning systems, it is known that it is frequently desirable to provide a means for facilitating the turning of air from one direction to another within the duct. Such turning of air in a duct not only assists in the delivery of air in a most efficient manner, but also reduces the energy requirements for delivering air around comers.
Accordingly, there has developed the use of turning vanes for assisting the turning of air. Such vanes are sometime of sheet metal construction. Other times they are constructed of a fibrous material, such as fiberglass formed and reinforced with plastic resin or the like. Examples of turning vanes are present in U.S. Pat. Nos. 4,467,829 and 5,529,092.
Often, the turning vanes are mounted on rails disposed on opposite sides of a duct, inside the duct, generally at the junction where the duct is enabling a change in direction of air flow. Usually, a plurality of vanes will be mounted in the duct at that location, to allow for the impingement of air at various locations where the turn in air flow is to be effected in the duct.
It is also known in the art to make the rails that hold the vanes out of sheet metal, and to perforate the sheet metal to allow for the formation of tabs from the sheet metal, which tabs may be bent at right angles to the rail to engage the vanes and hold them in place.
Where the vanes are of a fibrous material, it is known to have tabs inserted into the fibrous material, often with barbs or other sharp edges associated with the tabs, to engage inside the fibrous material of the vanes, in order to hold the vanes onto the tabs, to prevent the vanes from moving under any forces applied by blown air coming through the ducts and engaging the vanes.
However, the application of the tabs into the vanes tends to disturb the structural integrity of the vanes and can result in reducing the ability of the rail tabs to hold the vanes in place over time.